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14th October 2019, 12:13 #1
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How to calculate transformer winding losses
Hi,
We used a transformer from payton for +330V to 50V Half bridge LLC converter.Refer the datasheet attached,
In that transformer losses is given as 26W.
Also practically we observed the same losses in transformer.
Payton provide the loss details as below based on our request.
Core loss=5W.Copper losses=6W,Additional losses=15W
They told that additional loss is due to parasitic leakage inductanceAttachment 156028.
How to calculate these additional losses?

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14th October 2019, 17:20 #2
Re: How to calculate transformer winding losses
You attachment 156028 returns an "invalid attachment" error.
I am also curious what they mean parasitic leakage inductance losses.
What I can recall from leakage inductance; that it is uncoupled inductance that will ring with parasitic capacitances which will produce severe ringing. That ringing can generate a voltage breakdown in switching semiconductors, and must be snubbed. The snubbers, at least the simple ones, will dissipate that energy as heat in a resistor. Which of course is a power loss which reduces the efficiency.
But those are snubber losses. Transformers and inductor losses consist only of core or copper losses. And each has its own sublosses: i.e. copper may divided into RDC, skin effect, fringing, etc.My batteries are recharged by "Helpful Post" ratings.
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14th October 2019, 17:28 #3
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Re: How to calculate transformer winding losses
Hi,
To be honest: I don´t know the answer.
* maybe the copper loss is tested with DC. Then there are additional losses caused by AC: Proximity effect and skin effect.
***
About leakage inductance:
It causes the output voltage to be less than ideal... but the current is almost ideal: U_in x I_in is higher than U_out x I_out ... but I expect it to cause phase shift rather than heat.
KlausPlease don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.

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14th October 2019, 22:21 #4
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Re: How to calculate transformer winding losses
Did you try to detetmine the loss components yourself? The quoted statement can't be found in the datasheet. "Loss due to parasitic leakage inductance" doesn't sound like a serious substantiation. A possible explanation might be the difference between theoretical core losses of the basic transformer and real core losses according to fringing fields, flux perpendicular to main magnetic path etc.

15th October 2019, 00:13 #5
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Re: How to calculate transformer winding losses
Additional losses=15W
They told that additional loss is due to parasitic leakage inductance
and are proportional to load current  so 15W of extra Cu heating and full power, 7.5W at half power etc ...
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17th October 2019, 18:04 #6
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Re: How to calculate transformer winding losses
From the measured leakage inductance in the realized transformer,Is it possible to calculate the losses due to leakage inductance?
So that we can plan thermal constraints of transformer.

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17th October 2019, 20:15 #7
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Re: How to calculate transformer winding losses
it is part of the overall losses and does not lend itself to exact calculation  frequency makes a difference as does the shape of the currents flowing  no doubt the data sheet figures are derived from sine wave currents which give the lowest loss figures  heatsinking and max hot spot temp also affect losses ...

20th October 2019, 12:04 #8
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Re: How to calculate transformer winding losses
Yes, your transformer appears to be an planar transformer, and appears to have leakage inductance designed into it deliberately so its an “Integrated transformer” .
Deliberate designin of leakage inductance is common in LLC transformers, so there are not really losses associated with it (at least not directly). But I think you probably know this.
Though of course, if there is increased circulating current due to resonant component choices, than that will be like a conduction lossLast edited by treez; 20th October 2019 at 12:20.
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